KR20170070239A - Interfacial layers for solid-state batteries and methods of making same - Google Patents

Abstract

One or more interfacial layers in contact with the solid electrolyte and the hybrid electrolyte material include inorganic (e.g., metal oxides and soft inorganic materials) or organic materials (e.g., polymer materials, gel materials and ionic conductive liquids). The interface layer can improve the electrical properties of the interface between the cathode and / or the anode and the solid electrolyte (e.g., reduce the impedance). The interface layer can be used, for example, in a solid state battery (e.g., a solid phase ion conductive battery).

Description

TECHNICAL FIELD [0001] The present invention relates to an interfacial layer for a solid-state battery,

Relevant Application Cross Reference

This application claims the benefit of priority to U.S. Patent Application No. 62 / 069,748, filed October 28, 2014, and assigned to U.S. Patent Application No. 62 / 069,748, filed March 12, 2015, and U.S. Patent Application No. 62 / 131,955, The disclosure of which is incorporated herein by reference.

Statement on research or development by federal sponsorship

This disclosure was made with government support under DEAR0000384, which was awarded by the Department of Energy. The Government has certain rights in this disclosure.

Technical field

This disclosure relates to an interface layer for a solid state battery. Specifically, the present disclosure relates to an interfacial layer between a solid electrolyte and a cathode and / or an anode of a battery.

Solid state lithium batteries (SSLiBs) are used for the main problems encountered such as low stability, limited voltage, unstable solid electrolyte phase (SEI) formation and low cycling performance in a conventional lithium (Li) ion battery including a combustible liquid electrolyte. Provide a potential solution. Solid state electrolyte (SSE) is a possible material for successfully developing various solid state batteries, and various solid state batteries are SSLiBs for electric vehicle applications and solid state Na-ion batteries (SSNaBs) for large grid scale energy storage. Extensive SSEs have been investigated for LiSICON, TiO-LiSICON, perovskite, LiBH ₄ , sulfide-based glass / ceramics, Li-garnet for SSLiBs, and NASICON and beta-alumina for SSNaBs. With progressive advancement in ion conductivity enhancement in SSE, a high conductivity of 10 ^-2 S / cm in the sulfide-based electrolyte is obtained, which is comparable to the conductivity of the organic electrolyte. However, for a full-cell environment, a stable interface with a low interfacial impedance between the SSE and the electrode is important. Several approaches have been applied to reduce the interfacial impedance between the SSE and the cathode, including surface coating, interfacial softening, buffer layers such as LiNbO ₂ , Nb, BaTiO ₃ , and additives in the cathode composite, For example, it includes LBO. However, the interface on the anode side has hardly been studied, especially when a metal Li is used. This is due to the fact that many solid electrolytes, including perovskite-type (Li, La) TiO ₃ , NASICON (especially Ti-based materials) and sulfide-based glass electrolytes are not stable to metallic Li. Considering the fact that Li metal has the lowest potential as the anode (-3.040 standard hydrogen electrode) and the highest capacity (3860 mAh / g), the interface between SSE and Li metal anode for high energy density SSLiB development It is very important to solve.

Among the various SSEs, Garnett electrolyte has (1) a wide electrochemical window, stable to Li metal and up to 6V; (2) environmentally stable with processing flexibility; (3) SSLiBs are very attractive because they have a high ionic conductivity close to 1 mS / cm at room temperature. Since these discoveries decades ago, basic research has improved understanding of basic mechanisms and improved Li-ion conductivity. However, little progress has been made on the successful demonstration of high performance SSLiBs with Garnet SSE. A major challenge is the large interfacial resistance between the garnet electrolyte and the electrode material due to rigid ceramic properties. It has also been reported to heat or melt Li metal to integrate with Garnett's electrolyte. However, there is a tendency to limit the reduction in resistance at the interface due to the microgap present at the interface and potential wetting problems. It has been conventionally confirmed that Li ₂ CO ₃ is formed naturally on the garnet surface as a source of high interface resistance of Li metal and LLZO. After removal of surface impurities by polishing, a lower interfacial area specific resistance (ASR) to 109 Ω cm 2 was successfully achieved. Nonetheless, the interfacial impedance thus achieved is still too high for SSLiBs, and this polishing approach is only applicable to flat Garnet electrolytes and significantly limits cell geometry and manufacturing scalability.

SSLiBs, due to inherent safety, can provide a low cost safe energy storage solution for electrical vehicles, cell phones, and a variety of other applications. However, the SSLiB interface generally leads to high impedances due to low specific surface area, and also attempts to fabricate interfaces with 3D high surface area are deteriorated due to expansion / contraction due to voltage cycling, or electrode-electrolyte Can lead to high impedance due to low contact (e.g., pores) at the interface. Current SSLiBs current interface impedances are ~ 1000 Ω / ㎠, 100 to 1000 times higher than Li ⁺ batteries with organic electrolytes. This high interface impedance not only limits the initial rate performance of SSLiBs, but also significantly increases during charge / discharge cycling, which greatly affects battery cycle life. Thus, as a major problem, at the SSE-electrode interface, in particular (1) large interface impedances for charge transport and transport; And (2) mechanical degradation of the interface with an electrochemical charge-discharge cycle.

There is also a challenge with SSE that can account for limited success in SSLiBs and SSNaBs. This problem is solved by a large interface resistance in the cells between the electrode particles and the electrolyte particles, between the electrode particles, and between the electrolyte particles; Low structural interface integrity during cycling because SSE is generally weak; And high processing temperatures that are incompatible with most anode and cathode materials.

Therefore, there is a demand for a solid-state battery having improved electrolyte-electrode interface impedance characteristics.

The present disclosure provides an inorganic or organic interfacial layer having a thickness of 1 nm to 100 nm in contact with at least a portion of a solid state electrolyte (SSE) material, or one or all surfaces of a solid state electrolyte (SSE) material. Inorganic surface layer may be _{Al 2 O 3, TiO 2,} V 2 O 5, Y 2 O 3, and a metal oxide selected from the combinations thereof. The inorganic interfacial layer may be a soft inorganic material. The organic interfacial layer can be an ion conductive organic material comprising i ) a polymer, ii ) a gel material comprising at least one lithium salt and a polymer, or iii ) a lithium salt and at least one solvent.

The SSE material is a lithium perovskite material, Li ₃ N, Li- beta -alumina, lithium super ion conductor (LISICON), Li _{2 . 88} PO _{3 . 86 N 0 .14 (LiPON),} Li 9 AlSiO 8, Li 10 GeP 2 S 12, lithium SSE garnet material, lithium-doped garnet SSE material, lithium composite garnet material, and at least one selected from lithium combinations thereof ion-conducting SSE < / RTI > material. The SSE material may comprise a sodium-ion conducting SSE material selected from beta '' - Al ₂ O ₃ , Na ₄ Zr ₂ Si ₂ PO ₁₂ (NASICON), cation-doped NASICON, and combinations thereof. The SSE material may be a magnesium-ion conducting SSE material selected from Mg _{1 + x} (Al, Ti) ₂ (PO ₄ ) ₆ , NASICON-type magnesium-ion conductive materials, and combinations thereof.

The present disclosure also provides a device comprising at least one inorganic layer and / or organic interfacial layer. The device may be a solid-state ionically conductive battery and may further comprise an SSE material, a cathode material, and an anode material. The solid state ion conductive battery may be a lithium-ion conductive solid state battery, and the SSE material may be a lithium-ion conductive SSE material having one or more interfacial layers in contact with the lithium-ion conductive SSE material. The solid state ionically conductive battery may be a sodium-ion conducting solid state battery, and the SSE material may be a sodium-ion conducting SSE material having one or more interfacial layers in contact with the sodium-ion conducting SSE material. The solid state ionically conductive battery may be a magnesium-ion conducting solid state battery, and the SSE material may be a magnesium-ion conducting SSE material having one or more interfacial layers in contact with the magnesium-ion conducting SSE material.

For a lithium-ion conductive solid state battery, the cathode material may be selected from a lithium-containing cathode material, a conductive carbon material further comprising an organic or gel ion conductive electrolyte, and a polysulfide material and / or the anode material is a lithium metal , Silicon, optionally, a conductive carbon material further comprising an organic or gel ion conductive electrolyte, and air.  For a sodium-ion conductive solid state battery, the cathode material may be selected from a sodium-containing cathode material, a sulfur, a sulfur composite material, and a polysulfide material and / or the anode material may be an ion conductive sodium- Tin, phosphorous, and air. For a magnesium-ion conductive solid state battery, the cathode material may be a magnesium-containing cathode material and / or the anode material is a magnesium metal.

The solid-state ion conductive battery may further include a cathode-side current collector and / or an anode-side current collector. In any solid state ion conductive battery, the interface layer, the SSE material, the ion conductive cathode material, the ion conductive anode material, and the at least one current collector may form a cell, and the solid phase ion conductive battery may comprise a plurality of cells And adjacent pairs of cells are separated into bipolar plates.

For a fuller understanding of the nature and objects of the disclosure, reference is made to the following detailed description, taken in conjunction with the accompanying drawings, in which: Fig.
FIG. 1 is an ultra-thin ALD Al ₂ O ₃ that can reduce the interface impedance by conduction of Li and Na ions after lithiumation and sodiumation, and can expand and contract with the electrodes.
2 is a schematic view of an example of an interfacial layer and a high-voltage Li-NMC cell.
3 is a (schematic) graph of a procedure for producing a gel electrolyte showing that the gel electrolyte is pressurized with porous garnet pellets and filling the pores. This is shown in the following electron micrographs showing the garnet pellet (lower left) before hybridization to 50% porosity and the gel-electrolyte filled pores (lower right) after hybridization.
4 (a) is a cross-sectional SEM of a porous SSE sample after ALD Al ₂ O ₃ coating and Li metal infiltration. (b) are cross-sectional SEM and EDS at the Li-metal high-density SSE interface. The image demonstrates that the preferred Li weighing of the SSE is obtained.
Figure 5 (a) is a schematic atomic model for studying the ion diffusion at the interface. (b) is the charge model of the meso-scale space of the electrostatic potential at the interface.
6 is a schematic diagram of an example of SSLiBs with NMC-CNT-Garnet composite cathode, Li anode, and Garnet SSE. Non-combustible PFPE and gel-electrolyte can be used as the interlayer to reduce the interfacial impedance.
7 is a calculation technique for confirming the charge transport impedance, the surface decomposition products, and the atomic structure at the electrolyte-electrode interface.
Figure 8 shows the stability and SEM observations of the Garnet / Li metal interface. (a) is an XRD pattern comparison of LLCZN powder before and after heating with Li powder at 300 ° C for 12 hours. (b) is a cyclic voltammetric method of LLCZN having Li metal as the reference electrode and counter electrode and Pt as the working electrode. The scanning speed is 1.0 mV / s. (c, d) is a cross-sectional SEM image of LLCZN / Li (c) and having no coating LLCZN / Li (d) having a coating of Al ₂ O ₃ on-ALD LLCZN pellets.
9 is an electrical characteristic of a symmetric cell (Li / LLCZN / Li) with or without ALD coating. (a) is a schematic diagram of the symmetrical cell with a 1 nm ALD-Al ₂ O ₃ coating on the LLCZN, (b) is a Nyquist plot of electrochemical impedance spectroscopy (EIS); (c, d, e) are galvanostat circulations having current densities of 71, 157 and 300 / / cm2. (f) are the EIS after and after the plating / peeling cycle. The dashed line represents DC ASR after long cycling. (b) is an enlarged EIS at high frequencies. The cycling of cell Li / LLCZN / Li without ALD coating is also shown in (c).
10 is a high voltage cell having a Li metal anode and an LLZCN electrolyte. (a) is a schematic view of an entire cell designed using an ALD coated LLCZN, a Li metal anode, an LFMO / carbon black / PVDF composite cathode and a liquid organic electrolyte, and a FEC / FEMC / HFE (20:60:20, The composition of 1 M LiPF ₆ is added as an interfacial layer between the composite cathode and garnet electrolyte. (b) is the 1 st, 6 th, and 7 th cell voltage profiles of all the cells. The arrow indicates that a new interface layer has been added. (c) is the cycling performance. The arrows represent the seventh cycle of refilling the new liquid interface layer. (d) is an operating cell in which the LED device is turned on. The yellow pellet in the photo on the left is an ALD-treated LLCZN solid electrolyte. The LED is connected to the cell with the aid of plastic tweezers.
Figure 11 ALD-Al ₂ O ₃ Is the first major output of the Li metal and garnet interface depending on the presence or absence. Interfacial model of Li metal on LiAl ₅ O ₈ (a) and Li ₂ CO ₃ (b) from initial molecular mechanics simulation. Li different chemical potential (c) μ corresponding to Li metal _Li = 0 eV, and μ at the corresponding lithiated alumina in the range of Li chemical potential of _Li = -0.06eV (d) _Li = -1.23 eV and μ (e ) Is a Li potential large potential phase diagram (grand potential phase diagram) showing the phase equilibrium of the LLZO system.
12 is a SEM image of (a) chemical form and top (b) and side (c) images of a PVDF-HFP gel membrane.
Figure 13 is an EIS of garnet / cathode and garnet / gel / cathode cell.

While the claimed subject matter is described in terms of particular embodiments, other embodiments are also within the scope of this disclosure, including embodiments that do not provide all the benefits and characteristics described herein. Various structures, logic, process steps, and electronic variations may be made without departing from the scope of this disclosure or its scope.

The present disclosure provides a disposed interfacial layer (e.g., in physical contact) on a solid state electrolyte (SSE) material. The present disclosure also provides a method of fabricating such an interface layer and a device comprising such an interface layer. The present disclosure also provides hybrid electrolyte materials, and methods of making such devices and devices comprising such materials.

This disclosure is based on surprising and unexpected results that can significantly reduce the electrode-electrolyte interface resistance by incorporating the interface layers described in this disclosure. As described herein (e.g., Example 1 and FIG. 9), the integration of the interfacial layer can reduce the interfacial resistance by a factor of 300 so that solid-state battery performance can be put to practical use.

The present disclosure includes, for example, two types of materials as interfacial layers in a solid state battery.

1. Organic based polymers, gels, and liquid ion conductors. These include, for example, non-combustible, organic electrolytes, such as perfluoropolyether (PFPE) based electrolytes. These organic electrolytes were found to be essentially safe without fire. PFPE-based organic electrolytes can increase the interface across the electrolyte particle boundary, or the electrolyte-electrode interface, for example, to improve battery performance. PFPE-based electrolytes can support, for example, lithium ion chemistry. These PFPE-based electrolytes also have a much higher Li ⁺ transition number than regular electrolytes desirable for Li ion battery operation. The transition number is close to 1, similar to SSE. PFPE-based electrolytes significantly improve solid-solid contact, especially when volume changes occur during device operation. For example, PFPE is functionalized to form methyl carbonate-terminated PFPE (PFPE-DMCs). The functionalized PFPE is maintained as a liquid over a large temperature range and exhibits low toxicity. PFPE-DMSs were found to solvate, for example, the known bis (trifluoromethane) sulfonamide lithium salt (LiTFSI). It is the first time that noncombustible non-aqueous electrolytes have been used as interfacial layers in SSLiBs. Another example is, a polymer electrolyte or a gel electrolyte, for example, LiClO ₄ in a poly (ethylene oxide) (PEO) or polyvinylidene fluoride (PVDF) to be. Such a soft electrolyte can improve the contact between the electrode and the electrolyte for good charge transport and mechanical integrity. The gel electrolyte is highly elastic and can conformally coat the electrode or SSE surface and fill the SSE to form a high density pinhole member membrane (Figure 3). For example, the gel-electrolyte permeated into garnet powder can greatly increase the overall ionic conductivity. For example, a gel polymer electrolyte can be prepared as follows. 0.25 g of PVDF-HFP is dissolved in 4.75 g of acetone under 1 hour of robust stirring. This solution is then cast on a glass slice and the solvent is evaporated to a gel polymer film. The viscous gel electrolyte can be applied to the electrode or garnet electrolyte and dried. Filling the gel electrolyte in the garnet or electrode composite can be performed by vacuum filtration.

2. An inorganic-based solid phase interfacial material. For example, ALD ultra-thin oxide, which is ion-conductive and mechanically soft after lithiation, is used as an interface material. Electrochemically reacted Al ₂ O ₃ is soft and ionic conductive and improves the electrode-electrolyte interface. Metal oxides, such as TiO ₂ and Al ₂ O _3, are preferred interface layers after lithiumation. These oxides can be lithiated due to their small thickness even when they are electrically insulated. For example, an ultra-thin oxide deposited by atomic layer deposition (ALD) is effectively elastic and soft and can conformally coat electrode particles with Li and Na ions effectively conducted (FIG. 1). For example, the oxide after the electrochemical reaction of the first half cycle may be expanded up to 280% without any breakage or destruction. In addition, ALD-deposited Al ₂ O ₃ can effectively improve the wetting between Li metal and Garnett electrolyte. For example, ultra-thin (1-2 nm) conformal ALD Al ₂ O ₃ can effectively increase the wetting and penetration of metal lithium into porous garnet electrolytes (see, e.g., FIGS. 4 and 8). Soft, ionically conductive solids can improve contact and cycling performance with favorable mechanical softness and conductivity can be used. For example, β-Li ₃ PS ₄ (LPS) is softer than garnet. Soft LPS sulfide can be used as the nanoglue interface layer on the hard oxide garnet. According to the calculations, a small amount of LPS could improve charge transport between garnet particles. For example, LPS can be applied to SSE materials such as Garnet by dry milling, or LPS-Garnet composites can be synthesized by mixing precursors together. Composites with 95% garnet and 5% LPS are expected to have desirable processability, an electrochemically stable window, and high ionic conductivity.

In one aspect, the disclosure provides an interface layer. The interface layer is in contact with at least a portion of the solid electrolyte material. The interfacial layer may comprise an organic material or an inorganic material. Without being limited by any particular theory, it is believed that the interface layer reduces the impedance of the electrode-solid electrolyte interface by improving wetting of the electrode on the electrolyte surface, ion transport across the interface, structural integrity during cycling, .

The interface layer is ionic (e. G., Monovalent, divalent, or trivalent ionic). For example, the interface layer is lithium-ion conductive, sodium-ion conductive, magnesium-ion conductive, or aluminum-ion conductive. It is preferable that the interface layer is ion-conductive after formation of the interface layer or formed ion-conductive. For example, a specific interfacial layer, for example, a metal oxide layer, becomes ion conductive after lithiation or sodiumation after exposure to a Li or Na anode.

The interfacial layer can prevent the formation of harmful substances on the surface of the SSE. For example, the interfacial layer prevents the formation of harmful substances, such as Li ₂ CO ₃ , that reduce or interfere with ion transport between the electrode and the SSE.

At least a portion of the surface of the interface layer is in contact with at least a portion of the surface of the SSE material. The interfacial layer may contact both the surface (e.g., a continuous layer), or substantially all of the surface of the SSE material. The interface layer preferably contacts a portion or portions of the surface of the SSE material between the SSE material and the electrode material (e.g., the cathode material and / or the anode material). An interface layer that is in contact with a portion of the SSE material between the SSE material and the cathode (e.g., a soft, ionic conductive inorganic material interface layer or ionic conducting organic material interface layer) Layer) that is in contact with a portion of the substrate. For example, the interfacial layer that is in contact with a portion of the SSE material between the SSE material and the cathode is a soft, ionically conductive inorganic material interface layer or a soft, ionically conductive organic material interface layer, and a portion of the SSE material between the SSE material and the anode Is a metal oxide interface layer. The SSE material may have one or more of a cathode portion and an anode portion. The cathode material is disposed in the cathode portion of the SSE, and the anode portion is disposed on the anode portion of the SSE. The cathode portion and the anode portion of the SSE may have separate interface layers, and the individual interface layers may be the same or different.

The interfacial layer can have a wide thickness. The interfacial layer may have a thickness of from 1 nm to 100 nm and both include integer nm values and ranges therebetween.

The inorganic interfacial layer may comprise a metal oxide. For example, the interface layer is a metal oxide. Examples of the metal oxide include _{Al 2 O 3, TiO 2,} V 2 O 3, and Y ₂ O _3, but are not limited to these. Such a metal oxide interface layer can be referred to as a hard interface layer. The metal oxide interface layer may be formed by a method known in the art. For example, the metal oxide layer is formed by physical vapor deposition (e.g., sputtering) or chemical vapor deposition (e.g., atomic layer deposition (ALD)) or solution-based methods (e.g., sol-gel method) .

The inorganic interfacial layer may comprise a soft inorganic material. For example, the inorganic interfacial layer is a soft inorganic material. The soft inorganic material may be an ion conductive material. The soft inorganic material may be inherently conductive. Without being limited to any particular theory, a soft inorganic material can improve the contact between the electrode and the electrolyte and improve charge transport and mechanical integrity. Examples of soft inorganic materials include? -LiPS ₄ (LPS), Li ₁₀ GeP ₂ S ₁₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , glass ceramics such as Li ₇ P ₃ S ₁₁ , For example, Li ₂ S-SiS ₂ -Li ₃ PO ₄ . For example, sulfide-based soft-inorganic materials (e.g., sulfide-based solid electrolyte materials) are softer than garnet (e.g., LPS can be used as the interface layer of garnet-based SSLiBs). The soft inorganic material may form an individual layer on the SSE material.

The organic interfacial layer may comprise an ion conductive organic material (e.g., polymer and / or organic solvent), and optionally an ionic salt (e.g., Li salt, Na salt, etc.). Such an organic interfacial layer may be referred to as a soft interfacial layer. The ion conductive organic material is also preferably electrically conductive. For example, the organic interfacial layer may comprise a polymer (e.g., poly (ethylene oxide) (PEO)), a fluoropolymer such as polyvinylidene fluoride, a perfluoropolyether (PFPE) (Polyvinylidene fluoride- co -hexafluoropropylene). The ionic salt is soluble in the polymer. The polymer can be selected from the group consisting of, for example, And may further comprise a solvent (e.g., an organic solvent).

In another example, the organic interfacial layer comprises a gel material. The gel material may be an ion conductive gel material. Gel material is at least one metal-ion conductivity (for example, Li ⁺ conductivity, and Na ⁺ conductivity, and / or Mg ⁺ conductive) polymer and / or copolymer and / or metal-ion (e.g., Li ^+, Na ⁺ , And / or Mg ⁺ ) host polymers and / or copolymers and one or more ionic salts (e.g., Li salts, Na salts, Mg salts, etc.). The host polymer and the copolymer may solvate the metal-ion / ionic salt. Examples of polymers include poly (ethylene oxide) (PEO)), fluoropolymers such as polyvinylidene fluoride, perfluoropolyether (PFPE), or functionalized analogues thereof (e.g., methyl carbonate- Terminal PFPEs), but are not limited to, and examples of copolymers include, but are not limited to, poly (vinylidene fluoride-co-hexafluoropropylene) For example, LiPF ₆ , LiClO ₄ , bis (trifluoromethane) sulfonamide lithium salt, and combinations thereof. Ionic salts (for example, Li salts, Na salts, etc.) For example, an ionic salt (based on the total polymer present and the ionic salt present) is present in an amount of from 1 to 20% by weight, and both include a value of 0.1 and a range therebetween.

In yet another example, the organic interfacial layer is formed from a mixture of one or more solvents (e.g., organic solvents such as ethylene carbonate (EC), diethyl carbonate (DEC), fluorinated solvents (For example, Li salt, Na salt, and the like) and at least one ionic salt (for example, at least one compound selected from the group consisting of ethylene carbonate (FEC), methyltrifluoroethyl carbonate (FEMC), hydrofluoroether Ionic < / RTI > conductive liquids. For example, the salt is a lithium salt (e.g., LiPF _6, LiClO _4, bis (trifluoromethane) sulfonamide lithium salt, and combinations thereof). For example, the ionic salt is present in an amount of from 1 to 20% by weight (based on the total polymer present and the ionic salt present), and includes both a value of 0.1 and a range therebetween.

Soft ion conductive inorganic materials and soft ion conductive organic materials (e.g., polymeric materials, gel materials, or ionic conductive liquids) are soft materials. Softness means that this material can be compressed to fill voids (formed by, for example, SSE surface properties) to provide a continuous ionic conduction path between the electrode material and the SSE material. This soft interface layer is generally more ductile to allow electrode volume changes during cycling without structural failure.

The interfacial layer may be a discrete layer comprising a single inorganic interfacial layer material or a single organic interfacial layer material. The interfacial layer may comprise one or more discrete layers of inorganic interfacial layer material and / or organic interfacial layer material. The interface layer may be an individual layer comprising one or more inorganic interfacial layer materials and / or organic interfacial layer materials.

The interface layer is preferably a pinhole member. The interface layer may be free of observable pinholes. Pinholes can be observed either directly or indirectly by methods known in the art. For example, the pinhole may be indirectly observed by an imaging method (e.g., optical imaging, SEM imaging, and / or TEM imaging) and / or by electrical properties (e.g., resistance or resistivity) measurements .

Any SSE material can be used. Suitable SSE materials are known in the art. Suitable SSE materials are commercially available and can be prepared by methods known in the art.

The SSE material may be a lithium-ion conductive material. For example, SSE materials include porous or dense lithium-ion conducting SSE materials. Li-an example of the ion conductive material is a lithium SSE perovskite material _{(e.g., Li 0 36 La 0 .55 □} 0.09 TiO 3 (□ = vacancy _rate).), Li ₃ N (e.g., Li layer ₃ N), Li-? -Alumina, lithium super ion conductor (LISICON) (for example, Li ₁₄ ZnGe ₄ O ₁₆ ), Li _{2 . 88} PO _{3 . 86} N _{0 .14} (LiPON), Li ₉ AlSiO ₈ , Li ₁₀ GeP ₂ S ₁₂ , and lithium garnet SSE materials. Examples of the lithium garnet SSE material, Li ₃ - the lithium garnet SSE material (e.g., Li ₃ CTe ₂ O _12, where C is, for a lanthanide, for example, Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Ta, or combinations _{thereof, Li 3 + x Nd 3 Te} 2 - x O 12, where x is 0.05 to 1.5, Li ₅ - the lithium garnet SSE (For example Li ₅ La ₃ M ¹ ₂ O ₁₂ , where M ¹ is Nb, Zr, Ta, Sb, or a combination thereof, cation-substituted Li ₅ La ₃ M ¹ ₂ O ₁₂ , ^{_{Li 6 ALa 3 M 1 2 O}} 12, where a is Mg, Ca, Sr, Ba, or combinations _{thereof, Li 7 La 3 B 2 O} 12, where B is Zr, Sn, or combinations thereof); Li ₆ - phase Li garnet SSE material (e.g., Li ₆ DLa ₂ M ³ ₂ O ₁₂ where D is Mg, Ca, Sr, Ba, or a combination thereof, and M ³ is Nb, Ta, or combinations thereof); Cation-doped Li ₆ La ₂ BaTa ₂ O _12, cation-doped Li ₆ BaY ₂ M ¹ ₂ O ₁₂ , where the cation dopant is barium, yttrium, zinc, or a combination thereof, Li ₇ - Lithium garnet SSE material (e. G., Cubic Li ₇ La ₃ Zr ₂ O ₁₂ and _{Li 7 Y 3 Zr 2 O 12} ); cation-doped _{Li 7 La 3 Zr 2 O 12} ; Li 5 + 2x La 3, Ta _{2 -.. x} O _12, where x is 0.1 to _{1, Li 6 8 (La 2.95} , Ca 0.05) (.. Zr 1 75, Nb 0 25) O 12 (LLCZN), Li 6 4 Y 3 Zr 1. _{4 Ta 0. 6 O 12,} Li 6.5 La 2.5 Ba 0.5 TaZrO 12, Li 6 BaY 2 M 1 2 O 12, Li 7 Y 3 Zr 2 O 12, Li _{6 . 75} BaLa ₂ Nb _{1 . 75} Zn _{0 . 25} O ₁₂ , or Li _6.75 BaLa ₂ Ta _1.75 Zn _0.25 O ₁₂ ), a lithium garnet composite material (eg, a lithium garnet-conductive carbon matrix, optionally including sulfur). Other examples of lithium-ion conducting SSE materials include cubic garnet-type materials such as 3 mol% YSZ-doped Li _{7 .06} La ₃ Zr _{1 .94} Y _{0 .06} O ₁₂ and 8 mol% YSZ- Doped Li _{7 .16} La ₃ Zr _{1 .94} Y _{0 .06} O ₁₂ .

The SSE material may be a sodium-ion conductive material. For example, the SSE material can be selected from the group consisting of β "-Al ₂ O ₃ , porous or dense Na ₄ Zr ₂ Si ₂ PO ₁₂ (NASICON), cation-doped NASICON (eg, Na ₄ ZrAlSi ₂ PO ₁₂ , Na ₄ ZrFeSi ₂ comprises a material selected from the SSE _{PO 12, Na 3 Zr 1.} 94 Y 0. 06 Si 2 PO 12, Na 4 ZrSbSi 2 PO 12, and Na ₄ ZrDySi ₂ PO _12).

The SSE material may be a magnesium-ion conductive material. For example, the SSE material can be selected from the group consisting of Mg _{1 + x} (Al, Ti) ₂ (PO ₄ ) ₆ , NASICON-type magnesium-ion conductive materials (eg Mg _{1 -2x} (Zr _{1 -x} M _x ) ₄ P ₆ O ₂₄ ) and Mg _{1 -2x} (Zr _{1 - x} M _x ) (WO ₄ ) ₃ , where x is 0.01 to 0.5.

The interfacial layer and device may be fabricated using methods known in the art. For example, the metal oxide layer may be formed by physical vapor deposition (e.g., sputtering) or chemical vapor deposition (e.g., atomic layer deposition (ALD)) or solution-based (e.g., sol-gel) do. The polymer material, gel material, or ion conductive liquid layer may be formed by polymer or liquid coating methods known in the art. The layer of polymer material may be formed by a vacuum-based method.

For example, PFPE-based electrolytes can be filled into the garnet membrane by vacuum assisted methods. Hybrid electrolytes are expected to have much lower impedance than garnet tapes due to improved ion transport through the particles. The PFPE-LiTFSI electrolyte can be filled after assembling the symmetric cell with a configuration of Li / Garnet / Li. Impedance can be measured by varying the temperature to obtain activation energy and ionic conductivity. The EIS can be used as an interlayer to probe interfacial impedances before and after PFPE-based organic electrolytes. Garnet having different surface morphology and surface area can be produced.

In another example, the gel electrolyte can penetrate the garnet pores to form a solid / gel hybrid electrolyte, helping to overcome high interface resistance between the electrode and the solid electrolyte and to increase the conductivity on the electrolyte. Hybrid electrolytes can serve to prevent dendrite growth and penetration and allow high conductivity of conventional electrolytes within lithium metal secondary batteries. For example, the PVDF-HFP gel electrolyte was pressurized to 125 MPa with a porous Li _{7 .06} La ₃ Zr _{1 .94} Y _{0 .06} O ₁₂ garnet pellet as shown in FIG. As evidenced by electron micrographs in FIG. 3, garnet exhibits highly interconnected porosity filled with gel electrolyte after pressurization. When the gel electrolyte is placed under a high vacuum in the SEM, the high vacuum pressure compound volatilizes and the electrolyte decreases, leaving a void area that may not be present during the test.

ALD-oxides can improve Li-garnet wetting. For example, Li-metal may be coated on the garnet surface on the anode side. In order to increase the interfacial contact between Li metal and garnet, we can lead to the preferred wetting by applying ALD oxides (Fig. 4 (a) and (b)). The depth of Li metal filtration was found to depend on temperature and duration.

PFPE based electrolytes can be prepared using known methods. For example, a commercially available hydroxyl terminated PFPE having a nominal molecular weight of 1000 to 4000 g / mol may be modified to form methyl carbonate-terminated PFPEs (PFPE-DMC), with desirable thermal stability and flame resistance It is expected. PFPE-DMCs are expected to have the desired solubility of lithium salts such as lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). PFPE-DMC with LiTFSI dissolved as electrolyte is expected to have a high transition number t ~ 0.9 and is similar to Garnett's electrolyte.

Devices, for example, solid state batteries, may be formed using methods known in the art. For example, a layer-by-layer process known in the current LiB fabrication method can be used to fabricate a Li-garnet-NMC cell.

For example, CNTs can be used as binders and conductive additives. First, the Al foil is deposited with an NMC / CNT composite. Garnett tapes can then be produced at intermediate temperatures (< 500 ° C). PFPE or gel electrolyte can be filled in the device under vacuum.

In another example, the Li-metal on the anode side can be filled into the porous structure of the garnet electrolyte after coating the ALD oxide. By filling the gel electrolyte in the garnet pores, the interface impedance can be significantly reduced. The cell can be completed with a metal current collector. On a lap scale, an Al foil can be used for the cathode, and a Cu foil can be used for the anode. Bipolar metals can be used for cell stacking and integration. In order to improve the electrical contact between the electrode and the current collector, a thin film graphene layer can be applied. For example, a low-cost graphene ink may be used.

In another example, for ALD-garnet, a high density Li-rich garnet membrane is coated with an ALD oxide. A heating process was used to lithiate the oxide layer and increase the ionic conductivity to achieve an effective nanoscale glue. The ALD oxide can fill the pores to form a high density layer.

An example of the device structure is outlined in FIG. 6, wherein the Li metal is the anode, the NMC mixed with the filtered CNT and garnet is the cathode, and the garnet membrane is used as the electrolyte membrane. After packing the layer, the interlayer material may be filled with, for example, PFPE or a gel-based electrolyte to improve the interface. Fig. 2 shows an example of the fabrication of a whole cell layer-to-layer. The PFPE electrolyte can be vacuum filled at the end. The transport path of ions and electrodes may be provided by filtered conductive carbon (e. G., CNT or graphene) and Garnet SSE. The Li metal can be applied as an anode with the aid of an ALD oxide coating.

The hybrid electrolyte may comprise a soft organic material or a mixture of a soft inorganic material and an SSE material (composite material). For example, the composite material may comprise from 10 to 90% by weight of at least one soft organic material or soft inorganic material (based on the total soft organic material present or the soft inorganic material and the SSE material present) % Value and a range therebetween. Hybrid electrolytes can reduce the SSE interface impedance.

For example, a dry milling method can be used to form a conformal coating of LPS on garnet surfaces by mixing garnet particles and LPS and to improve the integrity of the structure and the interface of charge transport during the charge and discharge processes. For example, the composite electrolyte may be predominantly composed of garnet having about 5-10% LPS to improve the interfacial properties of the composite electrolyte. In a typical experiment, precursors of LPS and garnet electrolytes are mixed using previously known methods. The composite is then calcined, for example, in an inert atmosphere at 1000 캜 for 8 hours at a heating rate of 250 캜 / hour.

In one aspect, the disclosure provides a device comprising one or more interfacial layers and / or one or more hybrid electrolyte materials of the present disclosure. For example, a device is an electrochemical device such as a battery. Examples of the battery include a solid state battery or a flow battery. Examples of suitable battery constructions are known in the art.

The device may be a solid state battery. For example, the solid phase ionically conductive battery may comprise one or more of the interface layers of the present disclosure and / or one or more hybrid electrolyte materials of the present disclosure, and may further comprise SSE material, cathode material, and anode material.

Suitable electrode materials (cathode material and anode material) are known in the art. Suitable electrode materials are commercially available and can be prepared by methods known in the art.

The solid state battery may further include a cathode side current collector (for example, a conductive metal or a metal alloy) and / or an anode side current collector (for example, a conductive metal or a metal alloy). Metals and metal alloys suitable for current collectors are known in the art.

The interface layer, the SSE material, the ion conductive cathode material, the ion conductive anode material, and the one or more current collectors may be formed into cells. The solid state ion conductive battery may comprise a plurality of cells, and each adjacent pair of cells is separated by a bipolar plate.

The solid phase ionically conductive battery may be a lithium-ion conductive solid state battery, and the interface layer is an interface layer in contact with the lithium-ion SSE material. The cathode material may be selected from the group consisting of lithium-containing cathode materials (for example, Li (NiMnCo) _1/3 O ₂ (NMC), LiCoO ₂ , LiFePO ₄ , Li ₂ MMn ₃ O ₈ , M is Fe, Co, And the polysulfide material and / or the anode material may be selected from a lithium metal, a silicon-based material, a silicon-based material, (E. G., Graphite, carbon black, carbon nanotubes, and graphene) and oxygen (e. G., Air) optionally further comprising an organic or gel ion conductive electrolyte.

The solid phase ion conductive battery may be a sodium-ion conductive solid state battery, and the interface layer is an interface layer in contact with the sodium-ion SSE material. The cathode material is a sodium-containing cathode material _{(e.g., Na 2 V 2 O 5,} P 2 -Na 2/3 Fe 1/2 Mn 1/2 O 2, Na 3 V 2 (PO 4) 3, NaMn 1 _{/ 3 Co 1/3 Ni 1/3 PO 4} , and _{Na 2/3 Fe 1/2} Mn 1/2 O 2 @ graphene composite material), it may be selected from sulfur, a sulfur composite materials, polysulfide materials, and / Or the anode material may be selected from the group consisting of sodium metal, tin, phosphorus, and ion conductive, sodium-containing anode materials (e.g., Na ₂ C ₈ H ₄ O ₄ and Na _0.66 Li _0.22 Ti _0.78 O ₂ ) Air).

The solid phase ionically conductive battery may be a magnesium-ion conductive solid state battery, and the interface layer is an interface layer in contact with the magnesium-ion SSE material. For example, the cathode material may be a magnesium containing cathode material (e.g., doped magnesium oxide) and / or the anode material may be a magnesium metal.

The interfacial resistance of a device comprising one or more interfacial layers is less than 10 times, 20 times less, 30 times less, 40 times less, 50 times less, 100 times less, 200 times less than the resistance of the same device without one or more interfacial layers Or less, or 300 times or less. The interfacial resistance of the device including at least one interfacial layer is not more than 750 Ω · cm 2, not more than 500 Ω · cm 2, not more than 400 Ω · cm 2, not more than 300 Ω · cm 2, not more than 200 Ω · cm 2, Or less, 40 Ω · cm 2 or less, 30 Ω · cm 2 or less, 20 Ω · cm 2 or less, 10 Ω · cm 2 or less, 50 Ω · cm 2 or less, 4 Ω · cm 2 or less, 3 Ω · cm 2 or less, Cm &lt; 2 &gt;.

The following examples are presented to illustrate the present disclosure. They are not intended to be limited in any way.

Example 1

The following example provides an example of the preparation of the interfacial layer of the present disclosure.

The large interfacial resistance between the lithium metal anode and the Garnett electrolyte was solved using atomic layer deposition (ALD) using ultra thin aluminum oxide (Al ₂ O ₃ ). Li ₇ La _2.75 Ca _0.25 Zr _1.75 Nb _0.25 O ₁₂ (LLCZN) is used as a garnet material due to increased lithium-ion conductivity. A 300-fold reduction in DC interface impedance (from 606 Ω cm 2 to 2 Ω cm 2) was observed at room temperature, effectively preventing lithium-metal / garnet interface impedances. According to experimental and calculated results, it can be seen that the oxide coating enables wetting of the metallic lithium in contact with the garnet electrolyte surface, and the lithiated alumina interface allows effective lithium ion transport between the lithium metal anode and the garnet electrolyte. have. A working cell having a lithium metal anode, garnet electrolyte and a high voltage cathode has been demonstrated by applying the interfacial chemistry described herein.

Atomic Layer Deposition (ALD) by Garnet - like Li ₇ La _{2 . 75} Ca _{0 . 25} Zr _{1 . 75} Nb _{0 .} It has been demonstrated that by introducing an ultra-thin Al ₂ O ₃ coating on ₂₅ O ₁₂ (LLCZN), the wetting between Li metal and Garnet SSE is significantly improved and the DC interface is reduced 300 times to 2 Ω cm 2. Experimental and computational studies have shown that ALD-Al ₂ O ₃ It was used to investigate possible mechanisms for coating.

Characterization of garnet LLCZN solid electrolyte. Garnet-structured oxide Li ₇ La _2.75 Ca _0.25 Zr _1.75 Nb _0.25 O ₁₂ (LLCZN) was synthesized, sintered, and ground into thin film solid electrolyte pellets. The general Garnet composition is Li ₇ La ₃ Zr ₂ O ₁₂ (LLZO). When the La ^{3 +} site is substituted with Ca ^{2 +} and the Zr ^{4 +} site is simultaneously substituted with Nb ^{5 +} , the Li ion conductivity is increased and stabilized Cubic garnet has advantages of

Li metal and ALD-Al ₂ O ₃ Conformal interface between coated LLCZN. Based on the observed stability between the Li metal and the LLCZN garnet, the two step process was designed to achieve the conformal interface on the pellet LLCZN. First, ~ the ALD-Al ₂ O ₃ coating of a 1 nm thickness was applied to the garnet surface. Then, one Li metal foil was pressed onto the Garnet pellet using a hydraulic press at 50 psi, and then the laminated Garnet / Li pellets were heated at 250 DEG C for 1 hour under a small pressure. Control samples were prepared in the same manner using bare LLCZN pellets. For the ALD-Al ₂ O ₃ coated garnet, an intimate, conformal interface was observed by SEM (Fig. 8 (c)). On the other hand, the conformal reference sample exhibits a clear gap (Fig. 8 (d)), which is problematic since it can cause high interface impedances. Li metal can not wet Garnet LLZO until it has been heated for a long time (24-168 hours) at 300-350 ° C, much higher than the Li metal melting point of 180.5 ° C. Our two-step process of integrating Li metal with Garnet at relatively low temperatures does not cause color centers or cracks. This observed conformal interface of Garnet / Li is a direct result of the ALD oxide coating.

Interfacial Impedance of LLCZN / Li Metals. In order to investigate the interface impedance between Li metal and garnet LLCZN, symmetrical cell shown in Figure 9 (a) is ALD-Al ₂ O ₃ It was manufactured with or without coating. The cells are assembled by the same procedure and garnet is separated from the same batch of sintered pellets to isolate the effects of ALD and maximize consistency. The LLZCN pellet used had a thickness of 200 mu m and an electrode surface area of 0.49 cm &lt; 2 &gt;. All ALD coated samples had ~ 1 nm layer of Al ₂ O ₃ on exposed surfaces. The samples were measured by EIS at 22 ° C to determine the individual contribution to impedance. The obtained membrane is provided in Fig. 9 (b). In each sample, two distinct arcs appeared and were fitted by considerable circuitry. The bulk area specific resistance (ASR) is determined from the considerable circuit to find the high frequency x-intercept and is 26 and 28 Ω · cm 2 for the cell, respectively, with or without ALD coating. First arc represents a grain boundary impedance, the capacity is about the cells in accordance with the presence or absence ALD 3.1x10 ^-9 2.1x10 ^-9 F and F. The particle boundary ASR was found to be 150 Ω · ㎠ and 4500 Ω · ㎠ for the cell depending on the presence or absence of ALD coating. Since the garnet pellets used in the two cases use the same origin, the significantly higher ASR in the non-ALD sample results in lower interface contact (shown in Figure 8 (d) above) and particle boundary and Li-metal / Garnet interfacial impedance is due to overlap in frequency dispersion. The second arc is a characteristic of the interfacial impedance and the capacitance is 9.9x10 ^-4 and 2.8x10 ^-5 F for the cell with or without ALD coating. Since the interface ASR has two electrodes per cell, it was calculated by dividing the resistance by 2 before normalizing the electrode surface area. It can be seen that the ALD process reduces the interfacial ASR from 490 Ω · cm 2 to 16 Ω · cm 2 by the EIS. This reduction can in some cases be due to the following reasons: (1) conformal coating by Li metal and SSE contact increases the effective ionic transfer area; (2) spontaneously lithiated Al ₂ O ₃ formed in contact with Li metal at 250 ° C is Li-ion conducting and effectively transports ions between garnet and Li metal; (3) The ALD layer is deposited on the garnet surface with Li ₂ CO ₃ .

The present inventors conducted DC Li plating and peeling experiments to evaluate Li ion transport ability and interface impedance across the garnet and Li metal interface. The samples used for these measurements were the same as those reviewed above. At a current density of 71 μA / cm 2, Li / LLCZN / Li cells with ALD coating stabilized rapidly to ~2 mV. On the other hand, the control cell without ALD coating exhibited a noise polarized potential at 45 mV. Li / LLCZN / Li cells with ALD coating were cycled hundreds of times without any perceptible degradation. Figure 9 (d) shows a current density of 160 [micro] A / cm &lt; 2 &gt; in either direction for 20 minutes and 80 hours of cycling at a stable voltage response at ~ 4.5 mV. The current density increased to 300 [micro] A / cm &lt; 2 &gt;, resulting in a polarization voltage of ~8.5 mV (Fig. 9 (e)). According to the observed cycling with a small polarization, it is confirmed that a low interface impedance and a stable interface during Li cycling are obtained by the ALD oxide interface layer. Stable interface will due to the high durability of the lithiated Al ₂ O _3, in some cases, which is consistent with the literature on lithiated and mechanical properties of the sodium Chemistry Al ₂ O _3. The ASR calculated from the DC stripping / plating test is ~ 28 Ω cm 2, similar to the bulk ASR measured by EIS prior to the cycling test, indicating the effective removal of Li / garnet interface impedance and grain boundary impedance. To confirm this result, the cell impedance by EIS was measured again after cycling.

In Figure 9 (f), the EIS of the Li / LLCZN / Li cell after cycling is plotted according to the EIS before cycling and indicates the ASR calculated from the DC cycling. As shown in this figure, the remaining contributors to the impedance appear to be the bulk conductance of the electrolyte by matching between bulk ASR and DC ASR from the EIS before and after cycling. According to the lack of low frequency arc, it is confirmed that effectively preventing Li / Garnet interface impedance and grain boundary resistance. This effect is due to Li plating during cycling to improve the Li-metal / garnet interface and is due to an increase in the lithium content in the grain boundaries that potentially reduces the space charge contribution to the grain boundary impedance.

The electrical parameters of the two symmetric cells are summarized in Table 1 based on the EIS and DC cycling data. Note that no particle boundary impedance is observed after cycling and what is included in Table 1 does not contribute to the impedance. According to these results, the ultra-thin ALD-Al ₂ O ₃ The coating suggests facilitating Li-ion transport through the solid LLCZN / Li interface.

First principle calculation of Li metal and garnet interface. The first principle calculation was used to investigate the mechanism of interface improvement between Li metal and garnet after ultra thin ALD-Al ₂ O ₃ coating. First, the binding energy of Li metal on the lithiated alumina thin films of various Li stoichiometric Li _x Al ₂ O _{3 + x / 2} (x = 0.4 to 1.4) was calculated. These results demonstrate a strong chemical bonding energy between Li metals on Li _x Al ₂ O _{3 + x / 2} (x = 0.4 to 1.4), with a range of 6.0 to 11.4 eV / nm ² Lt; / RTI &gt; range. As a result, this strong interfacial bonding improves the wetting of Li metal to Al ₂ O ₃ coated solid electrolytes. Ultra-thin alumina after lithiation is a good Li-ion conductor and provides an effective Li-ion transport path between Li metal and garnet and low interface resistance. Garnet electrolytes it is difficult to manufacture, without any exposure to the air, Li ₂ CO ₃ is likely present on the surface garnet. Taking this into consideration, it is assumed that the thin film layer of Li ₂ CO ₃ covers the garnet. The interfacial bond energy between the Li metal and the Li ₂ CO ₃ layer is calculated as 1.6 eV / nm ₂ , which is significantly lower between Li and lithium alumina (Fig. 11 (a), (b)). The weak bonding energy leads to a low contact area, forming gaps and gaps. The presence of gaps, gaps, and Li ₂ CO _{3 in} the garnet / Li interface causes a large interface resistance. According to this calculation, the ultra-thin ALD-Al ₂ O ₃ Which is consistent with a remarkable reduction in interfacial impedance after coating.

Second, the chemical interfacial stability of Garnet / Li metal was calculated from the first principle. Based on the Li large potential state diagram of the LLZO system (Fig. 11 (c)), a small dissipation energy of -27 kJ / mole is produced for bare cubic LLZO in contact with Li. This decomposition corresponds to the composition of Li ₂ O, Zr, and La ₂ O ₃ and represents a potential tendency for Garnet's Li reduction. Compared to undoped LLZO, the doped Garnet LLCZN used in this study has similar phase stability for Li dissimilar compositions, Li metal with CaO and Nb, and phase equilibrium. The relatively small thermodynamic driving force for Garnet's Li reduction can account for the relative stability to Li metal. At high temperatures (&gt; 300 DEG C), the decomposition of garnet in contact with the Li metal can proceed and cause a significant volume expansion of up to 50%, based on the first principle calculations. This is supported by the experimental evidence of the low angular shift XRD peak of LLCZN that has been heated with Li metal. This large volume expansion at the interface can dissolve Garnett electrolyte and induce mechanical failure as previously shown in experimental studies. In addition, the decomposition of garnet electrolytes is similar to that of solid electrolyte phases (SEI), but forms an interlayer having low Li ion conductivity. This decomposed material may contain Li ₂ O / Li ₂ O ₂ , La ₂ O ₃ , Zr / ZrxO, CaO, Nb / NbO _{x and} may contain possible air contaminants which are detrimental to good interfacial ionic conduction, , La ₂ ZrO ₇ , Li ₂ CO ₃ . On the other hand, Li large cation state diagrams (Figs. 11 (d) and 11 (e)) show that garnet LLZO similar to LLCZN is stabilized with lithiumated alumina at equilibrium Li chemical potentials (μLi) of -0.06 eV to -1.23 eV. Thus, the introduction of an ALD-Al ₂ O ₃ coating protects garnet from decomposition through reaction with metallic Li and maintains a stable high conductive interface of the Li metal anode and garnet electrolyte. Experimental results by galvanostat cycling over extended periods of time without voltage increase are consistent with calculations for a stable interface between Li metal and ALD-coated garnet.

The innovative strategy was developed to address the interfacial problem between Li metal anodes and Garnet-type LLCZN solid electrolytes for all SSLiBs. The ultra-thin ALD coating of Al ₂ O ₃ effectively reduced the DC interface ASR from 606 Ω · cm 2 to 2 Ω · cm 2 by DC cycling and was significantly reduced by cycling at the grain boundary impedance. Action All cells have been demonstrated using high voltage cathodes LFMO, Garnet LLCZN, and Li metal anodes. A possible mechanism for interfacial improvement is proposed based on the following experimental and proofs of evidence: (1) ALD-Al ₂ O ₃ on Garnet The coating enables the conformal interface of Garnet / Li; (2) the high binding energy of the lithiated alumina improves the conformal interface; (3) ultra-thin lithiated alumina provides a high Li-ion transport pathway through the interface; And (4) Al ₂ O ₃ The coating can, in some cases, prevent formation of Li ₂ CO ₃ and garnet decomposition in contact with the Li metal, maintaining garnet / Li interface stability and observed electrical properties. These nanoscale interfacial engineering provide a common strategy for addressing interfacial problems between Li metal and SSE for all high energy density, safe, all SSLiBs.

Way. Material synthesis. LLCZN Garnett electrolytes were synthesized by sol - gel method. The initial materials were La (NO ₃ ) ₃ (99.9%, Alfa Aesar), ZrO (NO ₃ ) ₂ (99.9%, Alfa Asear), LiNO ₃ (99%, Alfa Aesar), NbCl ₅ And Ca (NO ₃ ) ₂ (99.9%, Sigma Aldrich). The stoichiometry of the chemical was dissolved in deionized water, and over 10% of LiNO ₃ was added to compensate for lithium volatilization during synthesis at high temperatures. Citric acid and ethylene glycol (molar ratio 1: 1) were added to the solution. This solution was slowly evaporated on a hot plate, a precursor gel was formed by stirring, heated to 400 DEG C for 10 hours, and the organics were burned. Then, the obtained powder was ball-milled, pressed with pellets, and fired at 800 DEG C for 10 hours. The synthesized powder was then uniaxially pelletized and sintered at 1050 DEG C for 12 hours in an alumina boat covered with the same powder. The resulting LLCZN pellets having diameters of 2.54, 1.27 and 0.79 cm were uniformly polished to a thickness of about 150-200 μm with a soft surface using fine sandpaper # 200, # 500, and # 1200 (LECO).

Characterization. SEM (Scanning Electron Microscope) was performed with a Hitachi SU-70 analytical scanning electron microscope. Phase analysis was carried out by powder X-ray diffraction (XRD) on a D8 Advanced with LynxEye and SolX (Bruker AXS, Wis., USA) using a Cu K? Radiation source operated at 40 kV and 40 mA.

Atomic Layer Deposition of LLCZN Electrolyte Pellets. The atomic layer deposition method was performed with BeneqTFS 500 of Al ₂ O ₃ deposition method. At 150 캜, high density nitrogen was used as the carrier gas for the entire process. Generally, for a 1 nm Al ₂ O ₃ coating, 10 ALD cycles were performed. Each cycle included another flow of trimethylaluminum (TMA, 4 sec, Al precursor) and water (4 sec, oxidant) separated by pure nitrogen gas flow (4 and 10 sec, carrier and scrubbing gas). The ultra-thin layer of Al ₂ O ₃ was evaluated by atomic force microscopy (AFM) on Si wafers according to control.

Assembly of Li metal coated LLCZN. Thin film Li foil disks (0.8 cm diameter and 0.2 mm thickness) were coated in a glove box filled with ultrahigh pure Ar with ALD-Al ₂ O ₃ Is placed on the treated LLCZN pellets and then the stacked Li / LLCZN pellets are heated at 250 캜 for 60 minutes and a pressure of 0.26 psi is applied by six stainless steel disks (1.5 g each). This small pressure was presumed to help the initial contact of the molten lithium on the garnet surface. For the control, the freshly polished LLCZN pellets were assembled with the lithium metal through the same procedure. After cooling to room temperature, a thin film lithium disk was adhered onto the pellet. A scanning electron microscope (SEM) was performed on the section of the sample obtained by separation by a tweezer.

First principle calculation. First principles calculations use the Vienna First Simulation Package (VASP) in a projector augmented-wave approach with a generalized-gradient approximation (GGA) of Perdew-Burke-Ernzerhof in high density functional theory. . Material entries of large potential state diagrams were obtained from the material project database. An interfacial model comprising a slab of amorphous Li metal and a slab of Li ₂ CO ₃ or lithiated alumina was equilibrated using a first molecular dynamic simulation at 513 K for 30 ps. The bond energy was calculated by subtracting the energy of the surface slab separated from the energy of the interface.

Example 2

The following example provides an example of the fabrication of the interfacial layer of the present disclosure.

These examples focus on Garnet-based SSE, but are expected to be applicable to other SSE chemicals. In order to obtain a low interface impedance solid state battery, it may be desirable to solve the following technical problems: a large interface impedance for charge transfer and transport; And the mechanical deterioration of the interface by an electrochemical charge-discharge cycle.

The interface of EIS of Garnet and LFMO electrodes was characterized. It can be seen that the structure on the surface of the garnet pellets reduces the interface impedance. A PFPE non-combustible solvent is prepared, the PFPE / LiTFSI electrolyte is tested, and is found to be electrochemically stable in the voltage range of 0-4.2 volts (v). A PVDF-HFP gel membrane was prepared and the stability and impedance of the ionic liquid electrolyte in the gel membrane were tested.

The characterization of the electrolyte / cathode interface, the impedance of the LLCZN solid state electrolyte and the interface impedance of the LFMO electrode were tested. The method and results are as follows.

_{LLCZN (... Li 6 8} (La 2.95, Ca 0.05) (Zr 1 75, Nb 0 25) O 12) Garnet was synthesized in the following manner: LLZO- CaNb was prepared by conventional solid-phase reaction. The initial materials, Li (OH), La (OH) ₃ , Ca (OH) ₂ , ZrO ₂ , and Nb ₂ O ₅ were mixed by flat ball milling and fired at 700 ° C for 48 hours (h). Li ₃ BO ₃ powder as an additive was prepared by heating a mixture of Li ₂ CO ₃ and B ₂ O ₃ at 600 ° C. The sintered LLZO-CaNb powder was prepared by flat ball milling with additives (both Al ₂ O ₃ and Li ₃ BO ₃ , Al ₂ O ₃ alone or Li ₃ BO ₃ Alone). The mixture was die pressed into pellets at 10 MPa and sintered at 790 DEG C for 40 h in air.

Synthesis of Li ₂ FeMn ₃ O ₈ (LFMO). LFMO was synthesized according to the modified literature. Briefly, the glycine-nitrate mixture solution was first prepared by dissolving lithium nitrate, iron nitrate, manganese nitrate (2: 1: 3, molar ratio) and glycine in deionized water. The molar ratio of nitrate to glycine is 2: 1. Then, the LFMO powder was obtained by annealing at 700 ° C for 2 hours after the combustion reaction of the glycine-nitrate solution at 300 ° C.

Battery assembly and electrochemical testing. Due to the sensitivity of Li metal to oxygen and moisture, all cells, including symmetric cells and all cells, are assembled in a glove box filled with ultra pure argon (99.999%) with moisture and oxygen levels below 0.1 and 0.01 ppm and tested . In a typical LLCZN / Li assembly, the Li foil was pressed to about 0.2 mm and then punched into a thin disk having a diameter of 0.79 cm. Li thin foil disk was distributed on one pair to a plastic tweezer-Al ₂ O ₃ coating on ALD one or both sides of LLCZN pellets and pressed gently. Six stainless steel (9 g in total) was placed on a Li foil. Then, the laminated Li / ALD-Al ₂ O ₃ coating LLCZN / Li cell is placed in an oven the glove box, followed by natural cooling to room temperature at 250 ℃ After heating for 1 hour. LLCZN / Li is ready for use. Stainless steel was used as current collector. The cathode disk was manufactured outside the glove box. The synthesized LFMO was thoroughly mixed with carbon black and PVDF in a mass ratio of 80:10:10 in NMP (solvent, N-methyl-2-pyrrolidone). This mixture was coated on clean, flat Al foil. After drying in air, the Al foil coated with the cathode slurry was placed in a vacuum oven and dried overnight at 110 ° C. And punched with a cathode disk (0.79 cm in diameter). Mass measurements were made with Microbalance (Sartorius). The whole cell was assembled by placing the cathode disk on the bare side of the Li / ALD-Al ₂ O ₃ -LLCZN pellets, and a small amount of high pressure organic electrolyte was added as a liquid interface layer between the cathode and LLCZN pellets. The assembled cell was secured using an alligator clip connected to an electric cable. The cell was kept in the glove box during all tests. These tests were performed with a BioLogic battery tester via feedthrough from a glovebox at room temperature (23-25 ° C). The cut voltage is 3.5 V and 5.3 V and the current density is 0.1 C (1 C = 150 mA / g).

Synthesis and Characterization of Gel and PFPE Based Materials. Nonflammable PFPE based electrolyte. PFPE-DMC was prepared by the following steps. First, fluorolink D10 and triethalamine in 1,1,1,3,3-pentafluorobutane were dissolved at 0 DEG C under stirring conditions and under a nitrogen atmosphere, and then 1,1,1, A solution of methyl chloroformate in 3,3-pentafluorobutane was added dropwise. After the mixture was stirred at 25 占 폚 for 12 hours, the PFPE-DMC product was obtained by filtration, washing with water and brine, and then evaporating under reducing atmosphere. The PFPE-DMC electrolyte is prepared by dissolving lithium bis (trifluoromethanesulfonyl) imide in PFPE-DMC and vacuum-filling it in a garnet membrane, which serves as an intermediate layer between the garnet electrolyte and the cathode material.

The cyclic voltammetry (CV) of the PFPE / LiTFSI electrolyte was tested using an assembled Li / PFPE / Ti structure in the CR2025 coin cell. The area of the cell is 1.98 cm 2 (radius = 5/16 inch) and the area of the titanium cathode is 0.712 cm 2 (radius = 5/32 inch). The voltage range is -0.3 to 4.2 V and the voltage scan rate is 1 mV / s.

The reaction current density is less than 0.002 mA in the region of 0.3 to 4.2 V and is very small. After several initial cycles, the CV curve becomes stable. According to these two facts, the PFPE electrolyte is electrochemically stable between 0-4 V. Also, for the PFPE electrolyte, no apparent peak appears in the voltage range of -0.3 to 4.2 V, which results in Li peeling at a voltage higher than 4.2 V and Li plating at a voltage lower than -0.3 V . The electrochemical stability of PFPE / LiTFSI in the voltage range of 0 to 4.2 V ensures that this electrolyte is stable in the reaction of the LLCZN garnet electrolyte lithium ion battery and can be used as an interface layer between garnet and cathode.

Gel based electrolyte. A PVDF-HFP based gel polymer was prepared by the following steps: 0.25 g PVDF-HFP was dissolved in a mixture of 4.75 g acetone and 0.25 g DI water (95: 5, m / m) for 1 h under continuous stirring. The solution was cast on an Al foil, and the solvent was evaporated at ambient temperature. Figure 12 shows the (a) chemical formula of the PVDF-HFP gel membrane, (b) the top surface and (c) the lateral SEM image. After drying for 2 h at 100 &lt; 0 &gt; C under vacuum, a homogeneous independent membrane was obtained.

The prepared porous membrane was prepared by mixing tetraethylene glycol dimethyl ether and n-methyl- (n-butyl) pyrrolidinium bis (trifluoromethanesulfonyl) amide in an argon-filled glove box with water and oxygen content of less than 0.1 ppm ) Imide (Py14TFSI) in 1 M LiTFSI in a 1: 1 volume ratio mixture at room temperature for 30 minutes.

The cyclic voltammetry (CV) test of the cell was set up to seal the polymer gel electrolyte membrane between the lithium and titanium disk and this configuration in the CR2032 coin cell. According to cyclic voltammetry at a scanning rate of 1 mV / s, it is suggested that the stable electrochemical window of this polymer gel electrolyte is at most 4.2 V. A sharp peak corresponds to Li plating at -0.2 V, and a peak around 0.1 V is due to Li peeling.

Figure 13 illustrates the effect of gel polymer on impedance reduction at the LLCZN electrolyte / LFMO cathode interface. The Pristin LLCZN electrolyte / LFMO cathode exhibits a large resistance of 300 k [Omega] x cm &lt; 2 &gt;, which is the bulk resistance of the electrolyte and cathode at medium and low frequency ranges, and also the significant interface resistance between the electrolyte and cathode. The introduction of the gel interfacial layer provides a high Li-ion conduction path, conformal and elastic contact between the electrolyte and the cathode and leads to a large reduction in interfacial resistance as shown in the mid-frequency range in the magnification plot. In addition, the EIS curve shows a different shape, which is made of Warburg-type impedance at low frequencies and corresponds to the capacitance behavior of the gold blocking electrode.

The interface impedance between the LLCZN garnet electrolyte and the LFMO electrode has been tested and it can be seen that the structure on the surface of the garnet pellet can reduce the interface impedance.

A PVDF-HFP gel membrane is fabricated and shows the preferred pore structure under SEM. The cycle electrochemical test shows that the gel electrolyte is electrochemically stable between 0-4.2V. This means that it can be used as an interface layer between the garnet electrolyte and the LFMO cathode. The EIS of LLCZN / gel / LFMO was tested. The overall impedance was reduced compared to the LLCZN / LFMO system without interfacial layer.

In addition, a non-flammable PFPE electrolyte was prepared. According to cycle electrochemical tests of the Li / PFPE / Ti system, this electrolyte is stable between 0-4.2v, which means that it can be used as an interface between the garnet electrolyte and the LFMO cathode.

Example 3

The following example provides an example of the fabrication of the interfacial layer of the present disclosure.

Based on the interfacial engineering method disclosed herein, SSLiB has been successfully designed and operated using Li metal anodes, garnet electrolytes and high voltage cathodes. This structure has a different interface layer for the anode (metal oxide) and the cathode (polymer / ionic conductive liquid). The electrical characteristics of this structure are shown in Fig.

Synthesis of Li ₂ FeMn ₃ O ₈ (LFMO). LFMO was synthesized according to the modified literature. Briefly, the glycine-nitrate solution was first prepared by dissolving lithium nitrate, iron nitrate, manganese nitrate (2: 1: 3, molar ratio) and glycine in deionized water. The molar ratio of nitrate to glycine is 2: 1. Then, after the combustion reaction of the glycine-nitrate solution at 300 占 폚, LFMO powder was obtained by annealing at 700 占 폚 for 2 hours.

Battery assembly and electrochemical testing. Due to the sensitivity of Li metal to oxygen and moisture, all cells including symmetric cells and complete cells were assembled and tested in a glove box filled with ultrahigh pressure pure argon (99.999%) at moisture and oxygen levels of less than 0.1 and 0.01 ppm . In a typical LLCZN / Li assembly, the Li foil was pressed to about 0.2 mm and then punched into a thin film disk with a diameter of 0.79 cm. Li thin foil disk was distributed on one pair to a plastic tweezer-Al ₂ O ₃ coating on ALD one or both sides of LLCZN pellets and pressed gently. Six stainless steel (9g in total) was placed on the Li foil. Then laid out the oven the Li / ALD-Al ₂ O ₃ coating stack LLCZN / Li cell in a glovebox, and then heated at 250 ℃ was cool naturally to room temperature. LLCZN / Li is ready for use. Stainless steel was used as current collector. The cathode disk was manufactured outside the glove box. The synthesized LFMO was thoroughly mixed with carbon black and PVDF in a mass ratio of 80:10:10 in NMP (solvent, N-methyl-2-pyrrolidone). This mixture was coated on clean, flat Al foil. After drying in air, the cathode slurry coated Al foil was placed in a vacuum oven and dried overnight at 110 ° C. And punched with a cathode disk (0.79 cm diameter). Mass measurements were performed with microbalance (Sartorius). _{Li / ALD-Al 2 O 3} -LLCZN by placing the cathode disc onto the bare side and assemble all the cells, a small amount of high-pressure liquid organic electrolyte of the pellets was added between the cathode and LLCZN pellets as liquid interface layer. The assembled cell was secured using an alligator clip connected to an electric cable. The cells were kept in the glove box for all tests. The test was performed from the glove box through the feedthrough at room temperature (23-25 ° C) with a BioLogic battery tester. The cut voltage is 3.5 V and 5.3 V and the current density is 0.1 C (1 C = 150 mA / g).

A working cell having a Li metal anode and an ALD coated LLCZN (e.g., Fig. 10 (a)). The effective interface between the developed Li metal anode and Garnett electrolyte can enable a potentially wide range of high energy density Li-ion batteries. Since Garnett's electrolyte is stable at a maximum of 6V, the high-voltage chemistry of Li ₂ FeMn ₃ O ₈ (LFMO) was chosen as the cathode material. A cathode electrode comprising LFMO, carbon black (CB), and polyvinylidene fluoride (PVDF, binder) was prepared by conventional slurry coating on Al foil. To improve the interface between the cathode composite and the garnet interface, a small amount of liquid organic electrolyte was added to form a cathode / electrolyte interface layer. It is known that organic electrolytes prepared by dissolving 1.0 M LiPF ₆ in a highly fluorinated solvent are stable up to 4.8 V. The test was carried out on an entire unsealed cell in a glove box filled with ultra-pure argon. 10 (b) shows the voltage profile of the first cycle at 0.1 C (1C = 150 mA / g). Two groups of well-defined congeals were observed at 4.0 V and 4.9 V for discharge, 4.1 V and 5.0 V for charge, demonstrating the action all cells and the Li metal anode as small over-potentials (0.1 V) . The cell has a coulombic efficiency of 83% in the first cycle and delivers a capacity of 103 mAh / g (70% theoretical specific capacity of LFMO). For the next five cycles, the generally degraded capacity (Figure 10 (c)) is due to the evaporation of volatile organic solvents in the interface layer. Nonetheless, the six cycles also exhibited a specific conformation of LFMO (Fig. 10 (b)). The cell test was stopped after the sixth cycle and resumed after refilling with a new organic electrolyte in the interfacial layer. As expected, the cell was immediately recovered and the capacity increased to 87% of the eigenvalue with a well defined charge / discharge geometry (Fig. 10 (b), (c)). 10 (d) shows a photograph of the working cell and supplies power to the light emitting diode (LED).

It is understood that the present disclosure is directed to one or more specific embodiments, but it is understood that other embodiments of the present disclosure may be made without departing from the scope of the present disclosure. Accordingly, the present disclosure appears to be limited by the accompanying claims and reasonable interpretations.

Claims (17)

An inorganic or organic interfacial layer having a thickness of 1 nm to 100 nm in contact with at least a portion of a solid electrolyte (SSE) material, or one or all surfaces of a solid electrolyte (SSE) material.
The method according to claim 1,
The SSE material may be a lithium perovskite material, Li ₃ N, Li-? - alumina, lithium super ion conductor (LISICON), Li _{2 . 88} PO _{3 . 86 N 0 .14 (LiPON),} Li 9 AlSiO 8, Li 10 GeP 2 S 12, lithium SSE garnet material, lithium-doped garnet SSE material, lithium composite garnet material, and at least one selected from lithium combinations thereof ion-conducting An inorganic or organic interfacial layer comprising an SSE material.
The method according to claim 1,
The SSE material is _{β '' - Al 2 O 3} , Na 4 Zr 2 Si 2 PO 12 (NASICON), cation-doped NASICON, and their sodium selected from the op-ion conductivity, including SSE substance, inorganic or organic Interfacial layer.
The method according to claim 1,
Wherein the SSE material is a magnesium-ion conductive SSE material selected from Mg _{1 + x} (Al, Ti) ₂ (PO ₄ ) ₆ , a NASICON-type magnesium-ion conductive material, and combinations thereof.
5. The method according to any one of claims 1 to 4,
Wherein the inorganic interfacial layer is a metal oxide selected from Al ₂ O ₃ , TiO ₂ , V ₂ O ₅ , Y ₂ O ₃ , and combinations thereof.
5. The method according to any one of claims 1 to 4,
Wherein the inorganic interfacial layer is a flexible inorganic material.
5. The method according to any one of claims 1 to 4,
Wherein the organic interfacial layer is an ion conductive organic material comprising i ) a polymer, ii ) a gel material comprising at least one lithium salt and a polymer, or iii ) a lithium salt and at least one solvent.
A device comprising at least one interface layer as claimed in any one of claims 1 to 7.
9. The method of claim 8,
Wherein the device is a solid state ion conductive battery and further comprises an SSE material, a cathode material, and an anode material.
10. The method of claim 9,
Wherein the solid phase ionically conductive battery is a lithium-ion conductive solid state battery, and the interface layer is the interface layer according to claim 2.
10. The method of claim 9,
Wherein the solid phase ionically conductive battery is a sodium-ion conductive solid state battery, and the interface layer is the interface layer according to claim 3.
10. The method of claim 9,
Wherein the solid phase ionically conductive battery is a magnesium-ion conductive solid state battery, and the interface layer is the interface layer according to claim 4.
11. The method of claim 10,
Wherein the cathode material is selected and / or selected from a conductive carbon material further comprising a lithium-containing cathode material, optionally an organic or gel ion conductive electrolyte, and a polysulfide material, or wherein the anode material is a lithium metal, A conductive carbon material further comprising an ion conductive electrolyte, and air.
12. The method of claim 11,
Wherein the cathode material is selected and / or selected from a sodium-containing cathode material, a sulfur, a sulfur composite material, and a polysulfide material, wherein the anode material is selected from an ion conductive sodium-containing anode material, sodium metal, tin, Device.
13. The method of claim 12,
Wherein the cathode material is a magnesium containing cathode material and / or the anode material is a magnesium metal.
16. The method according to any one of claims 9 to 15,
Wherein the solid state ion conductive battery further comprises a cathode side current collector and / or an anode side current collector.
17. The method according to any one of claims 9 to 16,
Wherein the interface layer, the SSE material, the ion conductive cathode material, the ion conductive anode material, and the at least one current collector form a cell, the solid phase ion conductive battery forms a plurality of cells, each adjacent pair Is separated by a bipolar plate.

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